1. Field of the Invention
The present invention relates generally to methods for enhancing the performance of conventional titanium alloys without a reduction in damage tolerance and, more specifically, to a method for producing homogeneous microstructure in the broad family of titanium alloys including, but not limited to Ti-6 wt. % Al-4 wt. % V, Ti-5Al-2.5Sn, Ti-6Al-2Sn-4Zr-2Mo-O.1Si.
2. Description of the Background Art
Titanium alloys offer attractive physical and mechanical property combinations that make them suitable for a variety of structural applications in various industries (e.g. aerospace) to obtain significant weight savings and reduced maintenance costs compared to other metallic materials such as steels. There have been several efforts to further increase the strength and stiffness of conventional titanium alloys to obtain enhanced performance. These approaches involve addition of particulates, short fibers, or continuous fibers that possess high strength and stiffness. Although these prior art approaches increase the strength and stiffness of conventional titanium alloys significantly, the increases are obtained with an accompanying drastic reduction in ductility and damage tolerance owing to the presence of brittle reinforcement, which restricts their usage in fracture-sensitive applications. A value of 5% tensile elongation is often considered in structural applications to separate ductile from brittle behavior.
Accordingly, a purpose of the present invention is to provide a novel methodology for producing titanium alloys with significant enhancement in strength and stiffness relative to conventional titanium alloys while maintaining adequate ductility. The method described herein involves addition of a small amount of boron below a critical level, and deforming the alloy at a specified range of temperature and deformation rate, to obtain uniform microstructure.